Mobile Core Network Node Redundancy

1. A pool proxy, for a communication network, the pool proxy comprising a processing circuit and being configured to: route signaling traffic between a radio access network node and one of a set of pooled core network nodes; operate in one of an active state and a passive state towards the radio access network node; when in the active state, to send a heartbeat signal to at least one of the pooled second core network nodes for relaying to a peer pool proxy; and when in the passive state, to receive a heartbeat signal from a peer pool proxy relayed via at least one of the pooled core network nodes; wherein, when the pool proxy is in the passive state, in the event that no heartbeat signal is received or the received heartbeat signal does not satisfy some minimum criterion, the pool proxy is configured to activate itself as pool proxy towards the radio access network node; wherein the radio access network node comprises one of a Base Station Controller and a Radio Network Controller; and wherein the set of pooled core networked nodes comprises one of a set of pooled Mobile Switching Centre (MSC) Servers (MSC-Ss) and a set of pooled Servicing General Packet Radio Service (GPRS) Support Nodes (SGSNs).

2. The pool proxy of claim 1 , wherein the set of pooled core network nodes comprises a set of pooled MSC-Ss, and wherein the pool proxy is being configured to operate as a Mobile Switching Center pool proxy, routing signaling traffic between the radio access network node and the set of pooled MSC-Ss.

3. The pool proxy of claim 2 , the pool proxy being further configured to operate as a Mobile Media Gateway and to communicate with each the MSC-Ss as Media Gateway Controller using a Gateway Control Protocol.

4. The pool proxy of claim 3 , wherein in the active state, the pool proxy is configured to convey the heartbeat signal to the pooled core network node(s) via a Stream Control Transmission Protocol association, and wherein the Stream Control Transmission Protocol association is shared with a Gateway Control Protocol interface.

5. The pool proxy of claim 3 , wherein in the active state, the pool proxy is configured to convey the heartbeat signal to the pooled core network node(s) via a Stream Control Transmission Protocol association, and wherein the Stream Control Transmission Protocol association is shared with an interface for carrying control signaling to and from the radio access network node.

6. The pool proxy of claim 3 , wherein in the passive state, the pool proxy is configured to receive the heartbeat signal from the pooled core network node(s) via a Stream Control Transmission Protocol association, the Stream Control Transmission Protocol association being shared with a Gateway Control Protocol interface.

7. The pool proxy of claim 1 , wherein the set of pooled core network nodes comprises a set of pooled SGSNs, and wherein the pool proxy is configured to operate as a SGSN pool proxy, routing signaling traffic between a Base Station Controller or the radio access network node and the set of pooled SGSNs.

8. The pool proxy of claim 1 , wherein the active state, the pool proxy is configured to convey the heartbeat signal to the pooled core network node(s) via a Stream Control Transmission Protocol association.

9. The pool proxy of claim 1 , wherein in the passive state, the pool proxy is configured to receive the heartbeat signal from the pooled core network node(s) via a Stream Control Transmission Protocol association.

10. The pool proxy of claim 1 , the pool proxy being configured to send and receive individual heartbeat messages of a heartbeat signal via ones of the pooled second nodes on a round robin basis.

11. A core network node in a communication network serving one or more radio access network nodes, the core network comprising one of a set of pooled core network nodes, the core network node further comprising a processing circuit and being further configured to: receive signaling from the radio access network nodes via an active pool proxy; and receive a heartbeat signal from the active pool proxy and to relay the heartbeat signal to a passive pool proxy; wherein the radio access network node comprises one of a Base Station Controller and A Radio Network Controller; and wherein the set of pooled core networked nodes comprises one of a set of pooled Mobile Switching Centre (MSC) Servers (MSC-Ss) and a set of pooled Servicing General Packet Radio Service (GPRS) Support Nodes (SGSNs).

12. The core network node of claim 11 , wherein the core network node is configured to relay the heartbeat signal via one of a Message Transfer Part Level 3 User Adaptation Layer (M3UA) or Signaling Connection Control Part (SCCP) relay.

13. The core network node of claim 11 , wherein the core network node is a MSC-S.

14. The core network node of claim 13 , wherein the core network node is configured to operate as a Media Gateway Controller using a Gateway Control Protocol to control Media Gateways implemented at both the passive and active pool proxies.

15. The core network node of claim 14 , wherein the core network node is configured to convey the heartbeat signal to the passive pool proxy via a Stream Control Transmission Protocol association, and wherein the Stream Control Transmission Protocol association is shared with a Gateway Control Protocol interface.

16. The core network node of claim 14 , wherein the core network node is configured to receive the heartbeat signal from the active pool proxy via a Stream Control Transmission Protocol association, and wherein the Stream Control Transmission Protocol association is shared with a Gateway Control Protocol interface.

17. The core network node of claim 11 , wherein the core network node is configured to convey the heartbeat signal to the passive pool proxy via a Stream Control Transmission Protocol association.

18. The core network node according to claim 17 , the Stream Control Transmission Protocol association being shared with an interface for carrying control signaling to and from the radio access network node.

19. The core network node of claim 11 , wherein the core network node is configured to receive the heartbeat signal from the active pool proxy via a Stream Control Transmission Protocol association.

20. A method of providing redundancy within a communication network comprising two or more pool proxies, the method comprising: maintaining one of the pool proxies in an active state towards the radio access network node; maintaining the other pool proxy in a passive state towards the radio access network node; routing signaling traffic between a radio access network node and one of a set of pooled core network nodes via the active pool proxy; sending a heartbeat signal from the active pool proxy to the passive pool proxy via one or more of the pooled core network nodes; and activating the passive proxy towards the radio access network node in the event that the heartbeat signal is not received at the passive proxy; wherein the radio access network node comprises one of a Base Station Controller and a Radio Network Controller; and wherein the set of pooled core networked nodes comprises one of a set of pooled Mobile Switching Centre (MSC) Servers (MSC-Ss) and a set of pooled Serving General Packet Radio Service (GPRS) Support Nodes (SGSNs).

21. The method of claim 20 , further comprising routing the heartbeat signals via the pooled core network nodes on a round robin basis.

22. The method of claim 20 , wherein the pool proxies are Mobile Switching Center pool proxies; the pooled core network nodes are MSC-Ss; and the radio access network node is one of a Base Station Controller and a Radio Network Controller.

23. The method of claim 22 , wherein the pool proxy is implemented at a Media Gateway which communicates with Media Gateway Controller functionality implemented at the MSC-Ss.

24. The method of claim 22 , further comprising sending heartbeat signals from the active pool proxy to the pooled core network node(s) over a Stream Control Transmission Protocol association shared with an interface for carrying control signaling to and from the radio access network node.

25. A method of providing redundancy within a communication network comprising two or more pool proxies routing signaling traffic between a radio access network node and one of a set of pooled core network nodes, the method comprising, at one of the pool proxies: maintaining the proxy in a passive state towards the radio access network node; receiving a heartbeat signal from one or more of the pooled second nodes; and activating the pool proxy towards the first node in the event that the heartbeat signal is not received; and upon activation of the pool proxy, routing signaling traffic between the radio access network node and one of the set of pooled core network nodes via the pool proxy; wherein the radio access network node comprises one of a Base Station Controller and a Radio Network Controller; and wherein the set of pooled core networked nodes comprises one of a set of pooled Mobil Switching Centre (MSC) Servers (MSC-Ss) and a set of pooled Serving General Packet Radio Service (GPRS) Support Nodes (SGSNs).

26. A method of providing redundancy within a communication network comprising two or more pool proxies routing signaling traffic between a radio access network node and one of a set of pooled core network nodes, the method comprising, at one of the pooled core network nodes: receive signaling from the radio access network node via an active pool proxy; receiving a heartbeat signal from the active pool proxy; and relaying the heartbeat signal to a passive pool proxy; wherein the set of pooled core networked nodes comprises one of a set of pooled Mobile Switching Centre (MSC) Servers (MSC-Ss) and a set of pooled Serving General Packet Radio Service (GPRS) Support Nodes (SGSNs).

27. A method of providing redundancy within a communication network comprising two or more pool proxies routing signaling traffic between a radio access neetwork node and one of a set of pooled core network nodes, the method comprising: routing signaling between said radio access network node and said pooled core network nodes when in an active state; sending a heartbeat signal to at least one of the pooled core network nodes for relaying to a peer pool proxy while in said active state; receiving a heartbeat signal from the peer pool proxy relayed via at least one of the pooled core network nodes while in a passive state; and switching from said passive state to said active state when no heartbeat signal is received from said peer pool proxy, or when the received heartbeat signal does not satisfy some minimum criterion; wherein the set of pooled core networked nodes comprises one of a set of pooled Mobile Switching Centre (MSC) Servers (MSC-Ss) and a set of pooled Serving General Packet Radio Service (GPRS) Support Nodes (SGSNs).

28. A non-transitory computer readable medium storing a computer program for controlling a pool proxy in a communication network comprising two or more pool proxies routing signaling traffic between a radio access network node and one of a set of pooled core network nodes, wherein the computer program comprises: code for routing signaling between said radio access network node and said pooled core network nodes when in an active state; code for sending a heartbeat signal to at least one of the pooled core network nodes for relaying to a peer pool proxy while in said active state; code for receiving a heartbeat signal from a peer pool proxy relayed via at least one of the pooled core network nodes while in a passive state; and code for switching from said passive state to said active state when no heartbeat signal is received from said peer pool proxy, or when the received heartbeat signal does not satisfy some minimum criterion; wherein the set of pooled core networked nodes comprises one of a set of pooled Mobile Switching Centre (MSC) Servers (MSC-Ss) and a set of pooled Serving General Packet Radio Service (GPRS) Support Nodes (SGSNs).